A known hybrid vehicle, which is mounted with an engine and a generator-motor that serve as drive units, and in which an improvement of fuel efficiency, a high output and an environmental protection are realized by taking advantage of each of the engine and the generator-motor, is in practically in use. According to the aforementioned type of the hybrid vehicle, it is pointed out that a weight distribution of the vehicle between front/rear portions thereof is not well-balanced and thus an operational stability may be reduced in a case where the engine, the generator-motor and a transmission are mounted on a front portion or a rear portion of the vehicle in a concentrated manner. On the other hand, on some of FR (front-engine/rear-drive) type vehicles where the engine is mounted on the front portion of the vehicle and rear wheels are driven via a propeller shaft, a transmission is mounted on the rear portion of the vehicle. This is for a purpose of improving the operational stability during high speed driving of, for example, a sports car, in consideration of the weight distribution of the vehicle between the front/rear portions thereof.
An example of a known drive unit is disclosed in JP2006-290187A (hereinafter referred to as Patent reference 1). According to the known drive unit disclosed in the Patent reference 1, the aforementioned techniques are combined with each other so that the imbalance of the weight distribution between the front/rear portions of the vehicle is reduced even in case of the hybrid vehicle. According to the known drive unit for the hybrid vehicle disclosed in the Patent reference 1, an engine is mounted on one of a front portion and a rear portion of the vehicle, a transmission is mounted on the other one of the front portion and the rear portion of the vehicle, and a motor is arranged either closer to the engine or closer to the transmission. Accordingly, the weight distribution between the front/rear portions of the vehicle is not as imbalanced so as to be regarded as a problem, and thus a possibility of a reduction in the operational stability is eliminated.
According to the Patent reference 1, the motor is arranged either closer to the engine or closer to the transmission, however, it is not easy to actually secure a mounting space. For example, in a case where the motor is additionally mounted on the conventional FR type vehicle where the transmission is mounted on the rear portion of the vehicle, there may be a need for a significant change in many peripheral parts and components in order to secure the mounting space, which tends to increase labor and/or costs. Further, an arrangement of the motor and/or a drive path to the transmission is restricted, and thus an efficiency of the motor and/or an efficiency of a power transmission may be reduced.
A need thus exists for a drive unit for a hybrid vehicle, which is not susceptible to the drawback mentioned above.